A large biodiversity of "skeneimorph" (Gastropoda: Vetigastropoda) species from the South Azorean Seamount Chain, with the description of seventeen new species

Forty-six “skeneimorph” species from the South Azorean Seamount Chain (SASC) have been studied. These comprise taxa in the superfamilies Trochoidea (family Skeneidae) and Seguenzioidea (families Trochaclididae, Pendromidae, Eudaroniidae and several genera which are not assigned to a family). Seventeen new species are proposed, fifteen in Seguenzioidea (Trochaclis fortis n. sp., Trochaclis carinata n. sp., Trochaclis platoensis n. sp., Adeuomphalus axistriatus n. sp., Adeuomphalus curvistriatus n. sp., Eudaronia spirata n. sp., Eudaronia mikra n. sp., Anekes anderswareni n. sp., Anekes mikrosculpta n. sp., Anekes umbilisculpta n. sp., Anekes varisculpta n. sp., Moelleriopsis atlantis n. sp., Moelleriopsis gritta n. sp., Moelleriopsis meteorminora n. sp., and Trenchia teriuga n. sp.) and two in Trochoidea (Mikro perforata n. sp., and Skenea basicarinata n. sp.). Three species are transferred to different genera: Xyloskenea xenos Hoffman, van Heugten & Lavaleye, 2010 is assigned to Trenchia, Trochus (Margarita) minima Seguenza, 1876 and Lissotesta scalaroides Rubio & Rolán, 2013 to Mikro. Twelve species (26%) are only known from the SASC and are probably endemic to this region. Twenty-one species are known from the SASC and/or the Azores seamounts and this set is probably endemic to this larger area. Five amphiatlantic species were found (11% of total species): Ganesa nitidiuscula Jeffreys, 1883, Rugulina fragilis (G.O. Sars, 1878), Trochaclis islandica Warén, 1989, Xyloskenea naticiformis Jeffreys, 1883 and Xyloskenea translucens (Dall, 1927). About 50% of the skeneimorph species found on the SASC are known from an extensive distribution area in the NE Atlantic and only few of them also live in the Mediterranean Sea. As usual on seamounts, the number of live-taken specimens is very low compared to empty shells of the thanatocenosis.